Export particles to xml
You can extract the particle coordinates using Python. I don't know what format XML you require but the following python code will extract the locations from the first particle system on the object named 'Cube' in the current scene and generate a fragment of XML defining each particle :

import bpy

object = bpy.context.scene.objects['Cube']
particles = object.particle_systems[0].particles

bpy.ops.text.new()

for p in particles:
    bpy.data.texts[-1].write("&lt;particle x='"+str(p.location[0])+"' y='"+str(p.location[1])+"' z='"+str(p.location[2])+"'/&gt;\n")


Simply open a Text Editor window, click 'New' to create a new text block and paste the above code. Amend the 'object = ...' line to change 'Cube' to the object owning the particle system and click 'Run Script'. This will generate a new text block (viewable in the Text Editor window) containing something like the following :

&lt;particle x='-1.0000001192092896' y='-0.590164840221405' z='-0.06581293791532516'/&gt;
&lt;particle x='0.44954031705856323' y='0.9999999403953552' z='-0.2284814417362213'/&gt;
&lt;particle x='-0.7184286713600159' y='-0.7630156874656677' z='-1.0'/&gt;
&lt;particle x='0.20344652235507965' y='0.9787259697914124' z='-1.0'/&gt;
&lt;particle x='-0.9999999403953552' y='0.39420998096466064' z='0.5528056025505066'/&gt;
&lt;particle x='0.9186654686927795' y='-0.5270229578018188' z='1.0000001192092896'/&gt;
&lt;particle x='-0.21842864155769348' y='-0.7690218091011047' z='-1.0'/&gt;
&lt;particle x='0.34407132863998413' y='-0.6609137654304504' z='-1.0'/&gt;
&lt;particle x='1.000000238418579' y='0.7620397210121155' z='0.39064347743988037'/&gt;
&lt;particle x='-0.31608468294143677' y='1.0000001192092896' z='-0.07232522964477539'/&gt;
&lt;particle x='1.0' y='-0.04655367508530617' z='-0.9907378554344177'/&gt;
&lt;particle x='0.06282128393650055' y='-0.8771299719810486' z='-1.0'/&gt;
&lt;particle x='-0.3629598319530487' y='-0.36061328649520874' z='-0.9999999403953552'/&gt;
&lt;particle x='1.000000238418579' y='0.5745397210121155' z='0.3185715079307556'/&gt;
&lt;particle x='-0.384637713432312' y='-0.23795989155769348' z='1.0'/&gt;
&lt;particle x='0.16828972101211548' y='-1.0000001192092896' z='0.44469761848449707'/&gt;
&lt;particle x='0.9999998211860657' y='-0.12467917054891586' z='0.9131660461425781'/&gt;
&lt;particle x='0.19794464111328125' y='-0.7613976001739502' z='1.0'/&gt;
....


Change the 'write' statement to change the format of the generated XML to whatever you require (currently it outputs each particle as a  node with attributes of 'x', 'y', 'z'). 

Code for Blender 2.82a